Hospitalization for acute general medical conditions is a common and often pivotal event for older Americans. Increasingly, such care is provided by "hospitalists", physicians who focus their practice on the care of hospitalized patients. Hospitalists have been shown in multiple studies to reduce hospital length of stay and costs, but their effect on outcomes and costs after discharge has not been well characterized. The aim of this project, entitled "Effects of Hospitalists in Medicare Data", is to develop and implement methods to use Medicare data to help determine the effects of hospitalists on the outcomes and costs of care for older patients. This will be accomplished by linking Medicare data to data on 6,000 older patients (Chicago Data) from an already-completed randomized multicenter trial of hospitalists that was funded by AHRQ and by development and piloting of a research protocol at the University of Chicago to study effects of hospitalists in Medicare data prospectively. Our Specific Aims are: (1) To evaluate the use of Medicare data to measure the outcomes of care for older patients cared for by hospitalists and non-hospitalists, including rates of hospital readmission, preventable hospitalization, and emergency department use in the period following hospitalization; (2) To evaluate the use of Medicare data to measure whether inpatient resource savings by hospitalists among older patients will be offset by higher resource use in post-acute care settings, including home health agencies (HHA), skilled nursing facilities (SNF), and rehabilitation facilities; (3) To develop and pilot a prospective research protocol to link Medicare data to clinical and survey data from older patients. The public health importance of this project is that it will lead to the refinement of methods to use Medicare data to determine if the inpatient cost savings that may result from hospitalist programs are offset by worse outcomes and increased resource use after hospital discharge. The methods developed and validated as part of the R21 will be used to seek support for an R01 that will apply these methods in a multicenter study of hospitalists. Determining whether the inpatient cost savings by hospitalists are offset by worse outcomes and increased resource use after hospital discharge are crucial concerns for Medicare patients and for the Medicare budget that could influence how Medicare policy responds to the growing use of hospitalists in the US. [unreadable] [unreadable] [unreadable]